HONEYWELL has hit back at a German motoring magazine article describing its new HFO-1234yf as a “killer refrigerant.”

While car manufacturers around the world look set to standardise on 1234yf as the replacement for R134a in vehicle air conditioning systems, environmental groups and others in Germany continue to raise concerns over its flammability and the potential release of highly toxic hydrogen fluoride in the case of a fire.

Andreas Kornath, an inorganic chemistry professor at Munich University, describes hydrofluoric acid is an insidious poison, “even a palm-sized wetting of the skin can be fatal within minutes if you do not take counter-measures,” he is quoted as saying.

The magazine article also questions why, if flammability of refrigerants is not an issue, that cheap hydrocarbons such as propane are not acceptable. It points out that the price of propane is less than 1 Euro per kg, and claims HFO-1234yf will cost from 150 to 200 euros.

Honeywell have refuted the claims and insist that 1234yf is 25,000 times less flammable than fuel. “It cannot even be compared with flammable refrigerants such as propane,” said Honeywell’s Sabine Chmielewski.

“Also, the velocity of the flame is very low and a flame will die down immediately on its own. The risk of HF formation is not higher than with R 134a – and this refrigerant has been used for decades without any recorded incident,” she added.

Germany, which originally backed CO2 as the replacement for R134a in car ac systems, continues to stand virtually alone in its opposition to HFO-1234yf.

The new gas has already been approved for use in the US, Japan and Europe and was recently given the all clear by the German firefighter association Deutscher Feuerwehr Verband (DFV) which said it was convinced it had the same safety standards as R134a. The DFV described the toxicity of R1234yf as low and comparable to R134a and was safe for passengers and emergency services.

The chemical manufacturers point out that HFO1234yf has undergone significant testing for safety and efficacy by independent testing groups, including the SAE International Cooperative Research Program, which comprises leading automakers. The SAE testing found HFO1234yf to offer “superior environmental performance” to CO2 while having “the lowest risk for use in mobile air conditioning systems in meeting environmental and consumer needs.”

Meanwhile, development of CO2 air conditioning continues in Germany with systems being considered for use in commercial vehicles.